Heating copper hydroxide produces copper oxide, CuO, a black solid. Copper oxide dissolves in acid, regenerating the copper (II) ion, which once again binds to water.

## Why should NaOH be added slowly to copper ions?

It is important to add the NaOH slowly, because you are adding a base to an acid. (This type of reaction generates a lot of heat). If your mixture warms up too much, you will skip step II and form the CuO directly-Step III.) If the solution is not basic, add an additional 5 mLs of NaOH.

## What is the theoretical yield of copper II nitrate?

theoretical mass of Cu(NO3)2 = 0.007921 mol x 187.6 g/mol = 1.47 g (3 sig.

## What is the theoretical yield of copper?

According to our balanced chemical equation, for every one mole of copper sulfate, we can make one mole of copper. The molar mass of copper is 63.546 grams per mole. If we multiply everything out, we’ll get 0.50722 grams of copper, which is our theoretical yield.

## What is excess reactant?

An excess reactant is a reactant present in an amount in excess of that required to combine with all of the limiting reactant. It follows that an excess reactant is one remaining in the reaction mixture once all the limiting reactant is consumed.

## How do you calculate percent yield of copper?

(b) If 3.91 g of copper was actually obtained, calculate the percentage yield of the reaction.

1. % yield = 100 x actual yield / theoretical maximum yield.
2. % yield = 100 x 3.91 / 3.99.
3. % yield of Cu = 98.0% (3 sf, 1 dp)

## What is the formula to calculate yield?

Current Yield It is calculated by dividing the bond’s coupon rate by its purchase price. For example, let’s say a bond has a coupon rate of 6% on a face value of Rs 1,000. The interest earned would be Rs 60 in a year. That would produce a current yield of 6% (Rs 60/Rs 1,000).

## What is a good DNA concentration?

To evaluate DNA purity, measure absorbance from 230nm to 320nm to detect other possible contaminants. The most common purity calculation is the ratio of the absorbance at 260nm divided by the reading at 280nm. Good-quality DNA will have an A260/A280 ratio of 1.7–2.0.

## What does a high 260 280 ratio mean?

Abnormal 260/280 ratios usually indicate that a sample is contaminated by residual phenol, guanidine, or other reagent used in the extraction protocol, in which case the ratio is normally low. Phenol C) Guanidine HCl and D) Guanidine isocyanate. High 260/280 purity ratios are not necessarily indicative of a problem.

## What is the A260 A280 ratio for pure DNA?

In buffered solutions, pure dsDNA has an A260/ A280 of 1.85–1.88 and pure RNA has a ratio of around 2.1. The A260/A230 is a sensitive indicator of contam- inants that absorb at 230 nm.